More than 600 ancient artefacts smuggled out of Iraq, recovered and lost again have been found among kitchen supplies stored at the prime minister's office.

The 638 items include pieces of jewellery, bronze figurines and cylindrical seals from the world's most ancient civilisations that were looted from the Iraqi National Museum in Baghdad after the 2003 invasion.

After their recovery, the US military delivered them last year to prime minister Nouri al-Maliki's office, where they were forgotten.

The artefacts, packed in sealed boxes, were misplaced because of poor co-ordination between the Iraqi government ministries in charge of recovering and handling archaeological treasures, said Tourism and Antiquities minister Qahtan al-Jabouri.

He blamed "inappropriate handover procedures" but did not go into detail.

Iraqi and world culture officials have for years struggled to retrieve looted treasures but with little success.

Thieves carted off thousands of artefacts from Iraqi museums and archaeological sites in the aftermath of the 2003 invasion and in earlier years of war and upheaval. Many items ended up abroad. Collections that were stolen or destroyed at the National Museum chronicled some 7,000 years of civilisation in Mesopotamia, including the ancient Babylonians, Sumerians and Assyrians.

Only a fraction of the items have been recovered.

So far, 5,000 items stolen since 2003 have been recovered. More than 15,000 pieces from the National Museum are still missing.